If you are not the owner of the records, first modify them to the current user or if you know what you are going to bulk update then select all the records in the view..

click on the three ... dots you will find the export to excel click that dropdown then click on the Open in Excel Online, then all the records selected will be shown in the excel gird view and then you start updating or enter the new values.

Once you are happy with the changes then click on the button Save changes to Dynamics

Then a pop will come up, where you can click on the Import link then it will take you the data import section on the dynamics 365...

Please see the below image for the successful imported data..

So you can navigate to the active account view on the dynamics 365.. and check all the changes have been reflected..

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This method is quite useful without using any tools on the dynamics 365...